1. Technical Field
The invention relates a method of making a local structure from an organic mandrel on a substrate at submicrometer dimensions.
2. Description of the Related Art
Over the past few years, the size of the integrated circuit has diminished substantially to submicrometer dimensions. As the size decreases, the challenge of making these small circuits increases. Manufacturing integrated circuits with specialized local structures, like local electrically conducting interconnects, is demanding at these submicrometer dimensions. Making these submicrometer structures is often difficult and time consuming, requiring the layering of different levels of films. Further, it has been difficult to make submicrometer structures in additional layers of film.
The prior art describes different methods for forming local submicrometer structures. Some methods rely on lithography alone to form these structures. Other methods use mandrels, or blocks of material with substantially vertical sidewalls. Several mandrel methods employ side wall image transfer processes to define an image below the side wall after removing the mandrel. For example, U.S. Pat. No. 4,838,991, assigned to the assignee of the current invention, discloses a method of defining the sidewall structures on the mandrel. In this method the mandrel is anisotropically etched to remove the horizontal surfaces, thereby leaving the mandrel's vertical sidewalls.
The prior art of fabricating local structures, such as electrical interconnects for submicrometer CMOS processor technology, is complex, expensive and requires specialized equipment. Fabrication uses many steps of depositing, etching and modifying the various films deposited on the integrated circuit. These steps often need specialized etchers and oxidation tubes and are difficult to use over multiple underlying films.
One object of the invention is to provide a simple way to define a local structure such as an electrical interconnect over multiple underlying films.
Another object of the invention is to add additional layers of film containing local structures at the submicrometer level.